Power has been restored at Ukraine’s Chernobyl nuclear power station, the site of the world’s worst nuclear disaster in 1986, the International Atomic Energy Agency said late Monday.

Separately, Ukraine’s state nuclear operator Energoatom accused the Russian military of detonating ammunition at the Zaporizhzhia nuclear power station in the country’s south.

“Ukraine has informed IAEA that external power had again today been restored to the (Chernobyl) Nuclear Power Plant after line had been again damaged ‘by the occupying forces’,” the UN’s atomic watchdog tweeted.

“Staff had restarted operations to reconnect the plant to the electricity grid.”

Energy operator Ukrenergo had earlier said the power line supplying the Chernobyl plant had been “damaged by the occupying forces,” after Russian forces invaded Ukraine on Feb 24 and seized the power station in the first days of the assault.

The retired Chernobyl nuclear reactors – enclosed in a giant steel and concrete sarcophagus – had also lost power early last week but supply was restored Sunday.

The power station has emergency diesel generators that can kick in when electricity is needed to power security systems including the cooling systems for the spent nuclear fuel storage facility, Ukraine’s nuclear power inspection body SNRIU said last week.

Ukrenergo said Chernobyl “cannot be left without a reliable energy supply”.

The 1986 explosion at the Chernobyl nuclear power plant killed hundreds and spread a radioactive cloud across Europe.

On March 4, Russian forces shelled and captured the Zaporizhzhia plant, Europe’s biggest nuclear power station, raising alarm in Europe over a possible nuclear catastrophe.

Ukraine’s Energoatom accused the Russian military of detonating ammunition near a reactor.

“And they are continuing to conduct explosions at Europe’s largest nuclear facility,” Energoatom said on messaging app Telegram, urging the International Atomic Energy Agency to take action.

It said it was currently unclear if radiation levels had changed at the station.

The IAEA said it was “aware of reports that Russian forces have carried out munition explosions at the site of the Zaporizhzhya Nuclear Power Plant today” and was seeking information about the situation from Ukraine.

Energoatom also claimed that 11 representatives of Russia’s state nuclear corporation Rosatom were at the Zaporizhzhia plant and taking part in the explosions, accusing Rosatom of violating “all established international rules and requirements of nuclear and radiation safety.”